A well equipped emergency medical technician (EMT) typically carries a portable defibrillator/monitor which allows the EMT to monitor or defibrillate a patient's heart. Several alternative constructions have been adopted by manufacturers of portable physiological units. The assignee of the current invention, Physio-Control Corporation of Redmond, Wash., has adopted a portable construction wherein the physiological unit has two components, an ECG monitor and a defibrillator. Such a construction is described in U.S. Pat. No. 4,096,856 titled "Portable Electronic Physiological Instrument Having Separable First and Second Components, and Improved Mechanical Connector Therefor" (herein incorporated by reference). In U.S. Pat. No. 4,096,856, a physiological instrument was disclosed that had first and second components that could be coupled together by sliding a grooved member located on one of the components onto a tongue member located on the other component. The tongue-and-groove construction allowed the two components to be mechanically attached together. When defibrillation and monitoring was required, both components could therefore be carded to the scene of an accident. When only monitoring was to be performed, however, the units could be separated, and only the monitor used. This construction has proved to be reliable and intuitive to use, and has gained wide-spread acceptance among emergency medical technicians.
While the tongue-and-groove mechanical connection of a defibrillator and monitor has proven to be a very flexible and successful design, there are still some disadvantages to connecting portable physiological devices in this manner. One of the problems presented by connecting two components with a sliding connector was designing an electrical connection that would allow the units to function cooperatively, such as by exchange of data or timing and control signals.
U.S. Pat. No. 4,097,113 to McKelvy titled "Electrical Connectors for Portable Electronic Physiological Instruments Having Separable First and Second Components" disclosed an electrical connector that was developed for interfacing a first and second component that were joined by a sliding tongue-and-groove (herein incorporated by reference). The electrical connector disclosed in McKelvy is constructed with opposing sets of leaf spring contacts, each set being wrapped around a central contact support member on the respective component. When the components were slid relative to each other to make the mechanical connection, the sets of electrical contacts were brought into engagement with each other. This allowed power and other signals to be transmitted between the defibrillator and the monitor.
While the electrical interface disclosed in McKelvy was sufficient for early defibrillators and monitors, its shortcomings arose as monitors and defibrillators became more complex. Most problematic was that the McKelvy connector was only able to provide limited communication capacity between the monitor and the defibrillator. As :monitors and defibrillators offering more complex functions were considered, it became desirable to pass additional control information and signals between the two components. The McKelvy design, while reliable and sturdy, is limited with respect to the number of communication lines provided, and also is a custom connection not adapted for use with commercially available multipurpose interfaces.